V. Ya. Bulanov

Production of nickel and iron nanopowders by hydrogen reduction from salts

The formation of nickel and iron nanoparticles produced by a chemical—metallurgical method and steels made of composite iron powders with nanosized nickel additions is studied. A procedure is developed for calculating the nanopowder particle size and the activation energy of sintering. The results obtained make it possible to decrease the temperature of the process of powder production, to decrease the energy consumed for powder sintering, and to predict the powder nanoparticle size.

Conglomeration of metallic power and destruction of conglomerates

Theoretical principles describing the formation and disintegration of conglomerates are developed and used to formulate a method for mixing nanodisperse, ultradisperse, and highly disperse powders, with simultaneous disintegration of conglomerates. The operation of the corresponding mixing equipment is described.

Vibroaeratic Mixing of the Powders in a Gas Medium: Report 2. Computing Kinematics of a Valve and Powder and Determining Optimum Sizes of Mixer Elements

Principles of determining the functional parameters and optimum sizes of a mixing chamber and its operating units were developed. Using the example of mixer operation at the vibration frequency f = 15 Hz and amplitude A = 0.006 m, the correction factors in the motion equation for dispersoids with open and closed valves were obtained. Graphs of the powder flow in the mixing chamber were plotted and analyzed. On this basis, the optimum sizes of the valve, which provide the assigned time mode of its opening, were found. The objective data of the mixer operation are given in the form of charge photography at × 200 magnification and diffractograms of mixture compositions for four samples.

Vibroaeratic mixing of the powders in a gas medium: Report 1. Developing a method and theoretical foundations for vibroaeratic powder mixing and destroying conglomerates

Based on the already-known theory of processes that occur with powders in the state of vibrationboiling, a new method for mixing the powder (vibroaeration) and a device for implementing it were developed. The following tasks are noted and completed: (i) qualitatively mixing powders with different granulometric compositions, including finely dispersed ones, during the complete destruction of their conglomeratic formations and (ii) developing theoretical foundations for the processes in the powder mass under the effect of a compressed gas “cushion” on it. Experimental testing for different engineering solutions is presented, and the optimum design version of a mixer is selected based on these tests.

Homogenization of doping elements in the Fe-Mo, Fe-Cu, Fe-Cr, and Fe-Ni nanosystems depending on the sintering time and temperature

This work is devoted to the solving a major problem of powder material science, specifically, prediction of the structural and phase composition during obtaining the new multicomponent materials using the mathematical description and development of computer software to simulate the homogenization processes of metal-metal binary systems. The processes of homogenization in solid nanosystems of the metals of type Fe-Mo, Fe-Cu, Fe-Ni, and Fe-Cr transition elements were investigated. A complex theoretical investigation of the homogenization of the particles in solid nanosystems is performed, analytical dependences of the degree of homogenization on the time and temperature of the sintering process are established, interdiffusion coefficients in the systems are calculated, physicochemical models of homogenization are suggested, and ways that a computer can analyze numerically with visualization of studied processes are developed. An evaluation of the convergence of the used numerical methods is performed, the accuracy of the calculations is evaluated, and an estimation of the calculations for the systems under consideration is carried out. The obtained results allow one to reduce the number of natural experiments in the development of new materials with specified properties.